Cholesterol is a sterol lipid found in the bloodstream and in the cell membranes of all body tissues.
The structure of cholesterol is as follows:

Cholesterol is composed of three regions: a hydrocarbon tail; a ring structure region with 4 hydrocarbon rings; and a hydroxyl group. The hydroxyl group is polar, which makes it soluble in water. The ring region and tail region are non-polar, so are soluble in organic solvents, but insoluble in water.
Medical practitioners and health advisors recommend reducing intake of cholesterol since elevated LDL blood cholesterol level (hypercholesterolemia) may lead to slow build up of cholesterol deposits in the walls of the arteries feeding the heart and brain, forming a plaque which can clog these arteries, a condition known as artherosclerosis. A clot (thrombus) that forms near this plaque can block the blood flow to part of the heart muscle and cause a heart attack. If such a clot blocks the blood flow to part of the brain, a stroke results. A high level of LDL cholesterol (160 mg/dL and above) reflects an increased risk of heart disease.
Chicken eggs represent a very high source of cholesterol (typically approximately 280 mgs per large egg) many medical practitioners and health consultants recommend eliminating eggs from the diet of those having high cholesterol blood serum concentrations. Consequently, for persons having cholesterol levels that are considered too high, conventional chicken eggs are almost eliminated as a source of food. This is somewhat unfortunate since eggs represent a substantial source of protein, vitamins, minerals and other nutrients in a form which is considered to be high in quality, nutrition and density while being relatively low in cost.
Because of the nutritional value of eggs, research poultry scientists have been experimenting to attempt to have chickens lay lower cholesterol eggs. One system, which has been tried, is the addition of foreign deleterious chemicals to the daily rations of egg laying hens. Also, hens have been injected with synthetic hormones to produce the desired reduction in cholesterol level. This present approach was prompted by the knowledge that cholesterol levels in the blood of humans can be controlled medically with hormones, calcium and magnesium ions, high doses of niacin and other vitamins and the use of throid active substances. As would be expected, such treatments exhibit in a great many instances deleterious and adverse side effects.
It has also been found that drugs are not cost effective as a feed supplement in lowering total blood cholesterol and improving the HDL/LDL ratio in barn animals (Luhman et al., Poultry Science 69: 852-855 (1990); Mori, et al., J.).
One method of reducing total cholesterol and improving the HDL-LDL ratio is by feeding animals especially chickens compounds that sequester bile salts which prevent their re-absorption by the lower small intestine causing their consequent excretion. Increased fecal bile acid excretion induces the liver to produce more bile acids, utilizing cholesterol as a substrate in its production. The resulting acceleration in LDL catabolism has the effect of reducing cholesterol content in the blood and improving the HDL-LDL ratio.
Chitosan is the only naturally occurring, positively charged polysaccharide, and is generally produced by deacetylation of chitin, a naturally occurring biopolymer, found in the cytoskeleton and hard shells of marine organisms such as crustacea, shrimps, crabs, fingi, etc.

It has been found that chitosan is able to absorb blood cholesterol in small animals (particularly mice and rats), as well as bile lipids, thereby lowering the blood levels of these molecules [J. Nutr. 2000; 130: 2753-2759]. A number of studies have shown that chitosan has the unique ability to lower levels of “bad” LDL cholesterol, while boosting “good” HDL cholesterol levels, thereby improving the HDL/LDL ratio.
Chitosan is biocompatible, non-toxic, and non-immunogenic, allowing its use in the medical, pharmaceutical, and cosmetic fields.
The soluble form of chitosan contains positively charged amino groups that are able to form ionic bonds with anionic compounds, including proteins and fatty acids. Additionally, chitosan may form hydrophobic bonds.
In order to use chitosan in aqueous solution, dissolution of the crystalline structure must take place. In hydrated crystalline chitosan, water molecules form columns between chitosan sheets and contribute to stabilizing the structure by making water-bridges between polymer chains. The hydrogen bonds are broken during the dissolution process of the chitosan using weak organic acids like acetic acid.
The mechanism of dissolution of polyelectrolyte powders is believed to involve the formation of a spherical grain structure. In pure water, this includes the rapid formation of a gel layer around the particle, followed by the slow release of polymer chains into the solvent. The slow process of polymeric chains leaving an aggregate was explained as being due to the effect of an attractive potential forming between the charged individual polymer and the electroneutral aggregate.
It is known that equilibration times for the dissolution of polyelectrolytes are often in the order of hours and even many days (Michel, R C et al. Biopolymers 53:19-39, 2000; Reed W F et al. Ber Bunzen Phys Chem 100: 685-695, 1996). The duration time of stirring of the chitosan solution is reported to be 12-24 h at room temperature Fredheim G E et al Biomacromolecules 4:232-239, 2003.
It has been found that chitosan is able to absorb blood cholesterol in small animals (particularly mice and rats), as well as bile lipids, thereby lowering the blood levels of these molecules [J. Nutr. 2000; 130: 2753-2759] A number of studies have shown that chitosan has the unique ability to lower levels of “bad” LDL cholesterol, while boosting “good” HDL cholesterol levels.
Cholesterol is a precursor of bile acids, which are steroid acids found mainly in the bile of mammals, having both a hydrophilic and a hydrophobic face. It has been suggested that chitosan reduces blood cholesterol by absorption of bile acids, causing increased use of cholesterol in further synthesis of bile acids, thereby removing cholesterol from the blood.
A food fiber supplement comprising chitosan and glucomannan has been shown to lower blood cholesterol in rats [J. Nutr. 2000; 130: 2753-2759] and in humans [J. Am. College Nutrition 2002; 21(5): 428-433]. However, large amounts of the fiber supplement were required in order to produce the cholesterol-lowering effect in humans, requiring the ingestion of fifteen capsules per day, providing 1.2 g/day each of chitosan and glucomannan. The total serum cholesterol in the human study was lowered by only about 7%, and the LDL cholesterol by 10%.
U.S. Pat. Nos. 7,067,146 and 6,814,975; U.S. patent Application No. 20050079204; and European Patent No. 1233682 to Eritocap teach use of chitosan together with eritadenine in the preparation of a foodstuff for reduction of cholesterol.
U.S. Pat. No. 6,323,189 and European Patent No. 1100344 teach a stable chitosan-containing liquid suspension for weight treatment.
U.S. patent Application No. 20050175763 teaches a phospholipd-containing stable matrix consisting of a supporting material in the form of a carbohydrate, such as chitosan. U.S. patent Application No. 20050100619 teaches a cholesterol-lowering supplement which may include chitosan and a phospholipid, together with a further composition capable of inhibiting cholesterol biosynthesis and a composition capable of increasing cholesterol metabolism.
Chitosan is unable to reduce cholesterol in the stomach, since it cannot absorb non-emulsified fats in the absence of bile salts, which are secreted only in the small intestine. Furthermore, chitosan dissolves and becomes positively charged in the acid conditions of the stomach, due to its functional amino groups. The highly charged polymer can react strongly with negatively-charged materials, such as phospholipids, which are present in the stomach, and become partially saturated. As a result, the amount of ingested chitosan having positively-charged groups available for interaction with the negatively charged bile acids after passing through the stomach is decreased.
There is thus a widely recognized need for, and it would be highly advantageous to have an improved mixture comprising chitosan which provides delivery of an increased proportion of unsaturated chitosan to the small intestine, for reducing blood cholesterol in animals, such as birds or mammals.